Acoustical tile

ABSTRACT

The present invention relates to an acoustical tile that includes a core and a surface treatment. The surface treatment comprises a formaldehyde-free latex binder, the binder including at least one formaldehyde-free biocide. The present invention also provides a process of manufacturing an acoustical tile.

BACKGROUND OF THE INVENTION

Acoustical tiles are specially designed systems that are intended toimprove acoustics by absorbing sound or reducing sound transmission inan indoor space, such as a room, hallway or conference hall, or thelike. Although there are numerous types of acoustical tiles, a commonvariety of acoustical tile is generally composed of mineral wool fibers,fillers, colorants and a binder, as disclosed, for example, in U.S. Pat.No. 1,769,519. These materials, in addition to a variety of others, canbe employed to provide acoustical tiles with desirable acousticalproperties and other properties, such as color and appearance.

Although, as discussed above, there are a variety of commerciallyavailable acoustical tile products, there are currently noformaldehyde-free acoustical ceiling products comprised of mineral woolfiber on the market today. A number of products classified as lowvolatile organic chemical (VOC) emitters are available, however, all ofthese products emit detectable levels of formaldehyde due to thepresence of various formaldehyde emitting components that are employedin these tiles. The inventors have found that certain polymeric bindersused in surface treatments and back coatings inherently contain,release, emit or generate formaldehyde. In addition, additives such aswet-state preservatives or biocides included in the surface treatmentsand back coatings can also release, emit or generate detectable andquantifiable levels of formaldehyde. Thus, even though formaldehyde maynot be a component of a polymeric binder or a biocide as used inacoustical tile, the tile may still release, emit or generateformaldehyde for a number of reasons, including, for example,degradation of the polymeric binder and/or biocide. Althoughformaldehyde emissions that are generated during heat exposure in themanufacturing process may be exhausted into the stacks or thermaloxidizers, the resulting product will still contain residualformaldehyde, which is emitted upon installation. A reduction informaldehyde emissions, or elimination of such emissions, will provideimproved indoor air quality in those locations where acoustical tilesare installed, such as schools, healthcare facilities, or officebuildings.

This invention provides an acoustical tile and a process ofmanufacturing an acoustical tile. These and other advantages of thepresent invention will be apparent to those skilled in the art in viewof the detailed description of this invention.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an acoustical tile that includes a coreand a surface treatment. Still further, the present invention provides aformaldehyde-free acoustical tile that includes a core and a surfacetreatment. The surface treatment includes a formaldehyde-free latexbinder and comprises at least one formaldehyde-free biocide.

Further, the present invention provides an acoustical tile and, stillfurther, a formaldehyde-free acoustical tile, each comprising a core anda surface treatment, wherein the surface treatment prior to dryingcomprises: from about 30 to about 50 weight % water; from about 40 toabout 60 weight % filler; from about 2 to about 15 weight % TiO₂; fromabout 2 to about 20 weight % formaldehyde-free latex; from about 0.25 toabout 1.00 weight % dispersant; from about 0.01 to about 1.00 weight %thickener; from about 0.10 to about 1.00 weight % surfactant; from about0.05 to about 0.50 weight % defoamer; and from about 0.01 to about 1.50weight % formaldehyde-free biocide.

Moreover, the present invention provides a process for manufacturing anacoustical tile and, still further a formaldehyde-free acoustical tile.This process comprises preparing an acoustical tile core and applying asurface treatment to the core, wherein the surface treatment includes aformaldehyde-free latex binder and comprises at least oneformaldehyde-free biocide.

Furthermore, the present invention provides a surface treatment. Thepresent invention also provides an acoustical tile treated with asurface treatment with no added formaldehyde or components that release,emit or generate quantifiable amounts of formaldehyde. Still further,the present invention provides a formaldehyde-free acoustical tiletreated with a surface treatment with no added formaldehyde orcomponents that release, emit or generate quantifiable amounts offormaldehyde.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic representation of a formaldehyde-free acousticaltile, in accordance with one aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises an acoustical tile. In accordance withanother aspect, the present invention also comprises a formaldehyde-freeacoustical tile.

As used herein, the term “formaldehyde-free acoustical tile” refers to atile that, as manufactured, releases or emits formaldehyde at a levelthat is below the quantifiable limits, that is, lower limit ofquantitation (lower LOQ), as established by the testing protocols of theStandard Practice For The Testing Of Volatile Organic Emissions FromVarious Sources Using Small-Scale Environmental Champers, dated Jul. 15,2004 (the Standard Practice), which incorporates a number of AmericanSociety for Testing and Materials (ASTM) standards, including ASTM D5116-97. Section 3.9.7.1 of the Standard Practice defines the lower LOQ“as the analyte mass that produces a response that is 10 times higherthan the instrumental noise level or is 10 times the standard deviationfor repeated analyses of a low level standard.” The termformaldehyde-free means that the amount of formaldehyde released oremitted is at below about the lower LOQ. In a preferred embodiment, theamount of formaldehyde released or emitted by the formaldehyde-freeacoustical tile of the present invention is typically at below about 2μg/m³. In a more preferred embodiment, the amount of formaldehydereleased or emitted by the formaldehyde-free acoustical tile of thepresent invention is typically at below about 1 μg/m³. Althoughacoustical tiles in accordance with the present invention are, asmanufactured, formaldehyde-free as defined herein, the acoustical tilespreferably are stored in a location and in a manner that will avoidexposure to VOC contaminants (specifically formaldehyde) that could beabsorbed by formaldehyde-free acoustical tiles.

Formaldehyde-free acoustical tiles in accordance with the preferredembodiment of the present invention are desirable for a number ofreasons, especially because of the adverse health and environmentalconsequences associated with VOC emitters, particularly formaldehyde.For example, formaldehyde has been classified by the InternationalAgency for Research on Cancer, part of the World Health Organization, asa human carcinogen. Legislative and regulatory bodies are increasinglyrequiring lower emission levels for formaldehyde. For example,California's Special Environmental Requirements, Specifications Section01350, in the Collaborative For High-Performance Schools (CHPS),includes emissions-testing procedures and maximum allowableconcentrations for selected VOCs, and is the first health-based buildingmaterial specification. A subsection of the CHPS Section 01350 focuseson the selection and handling of building materials with the goal ofminimizing the adverse impact of building materials on indoor airquality and occupant health, based on small chamber tests per the ASTM D5116-97 standard method. In 2004 CHPS was adopted the Standard Practice.

The Standard Practice also specifies procedures for specimen receiving,handling, and preparation. As specified in the Standard Practice, eachtest specimen is conditioned for 10 days±5 hours at 23±2° C. and 50±10%relative humidity, followed by a 96-hour test. The test method requireschamber air sampling at 24, 48, and 96 hour periods after initiating thechamber test, following completion of the conditioning period, based onsmall chamber tests as per the Standard Practice. Instrument calibrationand identification and quantification of individual compounds arerequired.

A formaldehyde-free acoustical tile in accordance with one aspect of thepresent invention, as illustrated schematically in FIG. 1, comprises anacoustical tile core 10, a surface treatment 20, and optionally abacking 30. An illustrative procedure for producing acoustical tile isdescribed in U.S. Pat. No. 1,769,519. In one aspect, the core 10comprises a mineral wool fiber and a starch, wherein the mineral woolfiber can include a variety of fibers, such as slag wool, rock wooland/or basalt wool. In another aspect of the present invention, thestarch component of the formaldehyde-free acoustical tiles can be astarch gel, which acts as a binder for the mineral wool fiber, as isdisclosed in U.S. Pat. Nos. 1,769,519, 3,246,063, and 3,307,651. In afurther aspect of the present invention, the acoustical tile core 10 cancomprise a glass fiber.

The acoustical tile of the present invention can be prepared using avariety of techniques. In one embodiment, the core 10 is prepared by awet- or water-felted process, as is described in U.S. Pat. Nos.4,911,788 and 6,919,132. The surface treatment 20 and backing 30, asdescribed herein, can also be applied to an acoustical tile prepared byway of a wet-felted process. Those of skill in the art will know how tomodify the surface treatment 20 and the backing 30 for application to awet-felted core 10. In a preferred embodiment, the core 10 is preparedby combining and mixing starch and a variety of additives in water toprovide a slurry. The slurry is heated to cook the starch and create thestarch gel, which is then mixed with mineral wool fiber. Thiscombination of gel, additives, and mineral wool fiber (referred to as“pulp”) is metered into trays in a continuous process. The bottom of thetrays into which the pulp is metered can optionally contain a backing 30(for example, a bleached paper, unbleached paper, or kraft paper-backedaluminum foil, hereinafter referred to as kraft/aluminum foil), whichserves to aid in the release of the material from the tray, but alsoremains as part of the finished product. The surface of the pulp can bepatterned, and the trays containing the pulp can be subsequently dried,for example, by transporting them through a convection tunnel dryer.Next, the dried product or slab can be fed into a finishing line, whereit may be cut to size to provide the acoustic tile core 10. The core 10can then be converted to the formaldehyde-free acoustical tile of thepresent invention by application of a surface treatment composition,which, after drying, provides the surface treatment 20 of the presentinvention. The surface treatment composition is preferably applied tothe core 10 after the core has been formed and dried.

As mentioned above, the core 10 of the formaldehyde-free acoustical tilecan also include a variety of other additives and agents. For example,the core 10 can include a calcium sulfate material (such as, stucco,gypsum and/or anhydrite), boric acid and sodium hexametaphosphate(SHMP). Kaolin clay and guar gum may be substituted for stucco and boricacid when manufacturing acoustical tile. In a further embodiment, thecore 10 can include, as a preservative, one or more formaldehyde-freebiocides, as described herein.

As previously discussed, acoustic tile in accordance with the presentinvention can optionally include the backing 30. Numerous materials canbe employed as the backing 30, including unbleached paper, bleachedpaper, kraft/aluminum foil, and the like. A flame resistant back coatingoptionally can be applied in combination with bleached or unbleachedpaper backing to improve the products surface burning characteristics.The flame resistant back coating can include a variety of components,such as, for example, water, a flame retardant, and a biocide. Thebacking 30 may also be employed for improving sag resistance and/orsound control. In addition, a fill coating or a plurality of fillcoatings may also be applied to the backing 30. The fill coating caninclude a variety of components, such as, for example, water, fillers,binders, and various other additives, such as defoamers, biocides, anddispersants.

The surface treatment 20 includes a formaldehyde-free latex, made fromnatural or synthetic polymers, and one or more formaldehyde-freebiocides. The formaldehyde-free latex, which provides the surfacetreatment 20 with film strength, includes a biocide that is not aformaldehyde emitter. As used herein, the term “formaldehyde-free latex”refers to a latex that is manufactured without the use of formaldehyde,or without the use of materials capable of generating or emittingformaldehyde, or both. In keeping with the invention, onlyformaldehyde-free biocides are included in the formaldehyde-free latexand thus the formaldehyde-free latex does not emit or generateformaldehyde, either as a by-product of drying or as a result of thebiocide included therein. Suitable materials for use in makingformaldehyde-free latexes include, for example: thermoplastic syntheticacrylic polymers, available as EI 8764 (Rohm & Haas); vinyl acrylicco-polymer, available as HP 31-316 NF; terpolymers of ethylene, vinylchloride, and vinyl acetate; homopolymers of polyvinyl acetate,available as PD 0062 (H.B. Fuller); copolymers of vinyl acetate andacrylic, available as Polyco® 3103 (Rohm & Haas); copolymers of styreneand acrylic, available as DL 218NA (Dow Chemical) and Acronal® 296D(BASF); epoxy polymer emulsions, available as Epi-Rez® 3510-W60(Celanese); polyurethanes; and polyvinyl alcohol, available as Airvol®(Air Products); or combinations thereof. Other suitable materials orthickeners for use in making formaldehyde-free latexes includewater-soluble polymers, such as cellulose ethers. Suitable celluloseethers include: methyl cellulose, available as Methocel™ A (DowChemical) and Culminal® (Hercules, Inc.); methylhydroxyethylcellulose,available as Tylose® MH300 (Shin Etsu); methylhydroxypropylcellulose,available as Methocel™ 228 (Dow Chemical); hydroxypropylcellulose,available as Klucel® (Hercules, Inc.); sodium carboxymethylcellulose,available as Tylose® C (Shin Etsu), CMC 7H (Hercules, Inc.), andCellosize™ CMC P-75-M (Dow Chemical); and hydroxyethylcellulose,available as Natrosol® 250 HBR (Hercules, Inc.), Cellosize™ WP-09 (DowChemical). Other suitable water soluble natural polymers suitable foruse include pregelatinized starches, available as Calbond™ (MGPIngredients, Inc.), and soy-protein derived polymers, available asProCote® 550 and ProCote® 4200 (DuPont Soy Polymers). As those skilledin the art will appreciate, the formaldehyde-free latex can comprise oneor more formaldehyde-free latexes. Further, in keeping with the presentinvention and in an effort to further reduce the emission offormaldehyde from acoustical tile of the present invention, theformaldehyde-free latex as made or supplied does not include a biocidethat emits or generates formaldehyde.

The surface treatment composition and backing 30 can both be appliedusing a variety of techniques readily known to and available to thoseskilled in the art, including, for example, airless spraying systems,air assisted spraying systems, and the like. The surface treatmentcomposition and backing 30 can also be applied by flow coating, floodcoating or with roll coaters. Drying the resulting product removes anywater and/or solvent used as a carrier for the surface treatmentcomposition or any of the components thereof and converts the polymerbinder into a structural, rigid network to provide surface treatment 20.

In keeping with the invention and in an effort to further reduce theemission of formaldehyde from acoustical tile of the present invention,the surface treatment includes, as a preservative, one or more biocides,none of which emits or generates formaldehyde. Preferably,formaldehyde-free biocide is added to the latex before the latex isapplied to the core as a component of the surface treatment. Forexample, the formaldehyde-free biocide can be added to the latex duringor even after the latex manufacturing process. The formaldehyde-freebiocide can serve as a preservative for the latex during transportand/or storage prior to its use as a component of the surface treatment.The formaldehyde-free biocide can serve as a preservative for theacoustical tile of the present invention.

Biocides serve to eliminate or inhibit an assortment of livingorganisms, including mold/mildew, fungi, yeast, algae, and bacteria.Thus, for example, biocides can include antimicrobial agents,anti-fungal agents, anti-bacterial agents, and the like. Suitableformaldehyde-free biocides include isothiazolin-3-ones, having the corestructure:

Preferred isothiazolin-3-ones include, for example,1,2-benzisothiazolin-3-one, available as Proxel® GXL or Proxel® CRL(ARCH Chemicals), Nalcon® (Nalco), Canguard™ BIT (Dow Chemical), andRocima™ BT 1S (Rohm & Haas). Other isothiazolin-3-ones include blends of1,2-Benzisothiazolin-3-one and 2-methyl-4-isothiazolin-3-one, availableas Acticide® MBS (Acti-Chem). Additional isothiazolin-3-ones include5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazoline-3-one,and blends thereof. Blends of 5-chloro-2-methyl-4-isothiazolin-3-one and2-methyl-4-isothiazoline-3-one are available as Kathon™ LX (Rohm &Haas), Mergal® K14 (Troy Chemical), and Amerstat® 251 (Drew Chemical).

Another suitable formaldehyde-free biocide includes zinc1-hydroxy-2(1H)-pyridinethione, available as Zinc Omadine® (ARCHChemicals), and is preferably effective in both the dry state and thewet state. Zinc 1-hydroxy-2(1H)-pyridinethione can also be employed withzinc oxide, available as Zinc Omadine® emulsion. Other suitableformaldehyde-free biocides include 2-n-octyl-4-isothiazolin-3-one,available as Kathon™ 893 and Skane® M-8 (Rohm & Haas), and2-(4-thiazolyl)-benzimidazole, available as Metasol® TK-100 (LanXess).

The biocides can be used individually, or in combination so long asneither the individual biocide, nor the combination of biocides employedemits or generates formaldehyde. Similarly, the amount of biocideincluded in the latex, in the surface treatment, and as combined in thelatex and in the surface treatment is not limited, so long as thebiocides do not emit or generate formaldehyde. It will be appreciatedthat if the latex is not manufactured to include a biocide, one or morebiocides can be added to the latex binder before it is applied to thecore, or before it is included in the surface treatment. Importantly,any such biocide or combination of biocides is selected such that thebiocide or biocides do not release, emit, or generate formaldehyde asthe latex is used or after drying.

The surface treatment 20 typically includes components in addition tothe formaldehyde-free latex binder and the formaldehyde-free biocide.For example, before the surface treatment composition is dried to formthe surface treatment 20, the surface treatment composition can bedispersed in a variety of solvents or carriers, such as water. Althoughwater is the most preferred solvent or carrier, a variety of othersolvents or carriers can be employed. The surface treatment 20 can alsoinclude numerous fillers, including, for example: air-floated,water-washed, or calcinated kaolin clay; precipitated or dry groundcalcium carbonate or limestone; or silicates, such as mica, glass,ceramic microspheres, feldspar, or nepheline syenite. In addition, thesurface treatment 20 can include diatomaceous earth, talc, gypsumcalcite, or zinc oxide. The fillers are desirably, added, for example,to adjust the color, rheology and hiding power or opacity of the surfacetreatment.

In addition, TiO₂ can be added to the surface treatment 20 to providebrightness and opacity. The surface treatment 20 can also include: adispersant, for dispersing the various solids and to keep them fromagglomerating; a thickener, for paint holdout and for developingapplication viscosity; a surfactant; and a defoamer, for minimizing airentrainment. The dispersant, thickener, surfactant, filler, and defoamerare selected so as not to emit or generate formaldehyde.

A variety of dispersants, thickeners, surfactants, and defoamers can beemployed in the surface treatment of the formaldehyde-free acoustic tileof the present invention. Suitable dispersants include tetra potassiumpyrophosphate (TKPP) (FMC Corp.) and the sodium salt of polycarboxylate,available as Tamol® 731A (Rohm & Haas). An example of a thickener ishydroxyethyl cellulose, available as Natrosol® (Hercules, Inc.). Anillustrative surfactant is ethoxylated nonylphenol, available as IGEPAL®CO-630 (Rhodia Canada, Inc.). An exemplary defoamer is an oil baseddefoamer, available as Hi-Mar DFC-19 (Hi-Mar Specialties, Inc.). Asthose skilled in the art will appreciate, the surface treatmentcomposition can comprise one or more of each of the dispersant,thickener, surfactant, filler, and defoamer.

A variety of formulations of surface treatment can be employed. In oneembodiment, the formulation of the surface treatment 20 comprises fromabout 30 to about 50 weight % water, from about 40 to about 60 weight %filler, from about 2 to about 15 weight % TiO₂, from about 2 to about 20weight % latex, from about 0.25 to about 1.00 weight % dispersant, fromabout 0.01 to about 1.00 weight % thickener, from about 0.05 to about0.50 weight % defoamer, from about 0.1 to about 1.0 weight % surfactant,and from about 0.01 to about 1.50 weight % biocide. More preferably, theformulation of the surface treatment 20 comprises from about 35 to about40 weight % water, from about 45 to about 55 weight % filler, from about2 to about 5 weight % TiO₂, from about 3 to about 8 weight % latex, fromabout 0.50 to about 1.00 weight % dispersant, from about 0.01 to about0.15 weight % thickener, from about 0.05 to about 0.20 weight %defoamer, from about 0.1 to about 0.5 weight % surfactant, and fromabout 0.01 to about 1.10 weight % biocide. Even more preferably, theformulation of the surface treatment 20 comprises from about 35 to about38 weight % water, from about 52 to about 57 weight % filler, from about2.50 to about 3.75 weight % TiO₂, from about 5 to about 8 weight %latex, from about 0.75 to about 1.00 weight % dispersant, from about0.05 to about 0.10 weight % thickener, from about 0.10 to about 0.15weight % defoamer, from about 0.20 to about 0.50 weight % surfactant,and from about 0.025 to about 0.60 weight % biocide.

In another aspect, the present invention provides a process ofmanufacturing a formaldehyde-free acoustical tile. The method comprisespreparing the acoustical tile core 10 and applying the surface treatmentcomposition to the core 10 to form the surface treatment 20. The surfacetreatment composition and surface treatment 20 comprise aformaldehyde-free latex binder and one or more formaldehyde-freebiocides.

The following examples further illustrate the invention but, of course,should not be construed as in any way limiting its scope.

Example 1

In this example a number of acoustical tiles were produced and testedfor formaldehyde emission in accordance with the Standard Practice. Theresults are provided in Examples 1-7. Examples 1 and 2 provideformaldehyde emission data for two standard acoustical tiles. Example 3provides formaldehyde emission data for an acoustical tile thatcomprises a core and a fire resistant back coating. Example 4 providesformaldehyde emission data for an acoustical tile of the presentinvention that comprises a core, a fire resistant back coating, and asurface treatment comprising a formaldehyde-free latex, wherein theformaldehyde-free latex includes a formaldehyde-free biocide. Example 5provides formaldehyde emission data for an acoustical tile of thepresent invention as described in Example 4, except that the acousticaltile of Example 5 also includes an additional biocide that was added tothe surface treatment composition. Examples 6 and 7 provide formaldehydeemission data for acoustical tiles of the present invention thatcomprise a core, a fire resistant back coating, and a surface treatmentcomprising a formaldehyde-free latex and a formaldehyde-free biocide.

TABLE 1 Quantification of Formaldehyde Emission Chamber ConcentrationExample Description (μg/m³) (1)^(a,b,c,d) Cast Acoustical Ceiling Panel3.7 (2)^(a,b+,c,d) Cast Acoustical Ceiling Panel 3.2 (3)^(a,b+) Core w/:Below the lower LOQ (1) Fire resistant back coating (4)^(a,b+,e,f) Corew/: Below the lower LOQ (1) Fire resistant back coating; (2) A surfacetreatment including: (a) a formaldehyde-free latex (5)^(a,b+,e,g) Corew/: Below the lower LOQ (1) Fire resistant back coating; (2) A surfacetreatment including: (a) a formaldehyde-free latex; (b) aformaldehyde-free biocide (6)^(a,b,e,g) Frost ™ ClimaPlus ™ Below thelower LOQ (Acoustone ®) (7)^(a,b,e,g) Summit ™ ClimaPlus ™ Below thelower LOQ (Acoustone ®) ^(a)The core includes rock wool, starch, stucco,boric acid, and SHMP, and is made by a cast process (Frost Acoustone ®)^(b)The fire resistant back coating includes water and a flame retardant(available as Pyrobreak ™ EX 18-USG). ^(b+)The fire resistant backcoating includes water, a flame retardant (available as Pyrobreak ™ EX18-USG), and a biocide (available as Zinc Omadine ® emulsion). ^(c)Thelatex used in this example is a vinyl acrylic co-polymer, available asHP 31-316. ^(d)The biocide used in this example is a combination ofMetasol ® D3T and Metasol ® TK100. ^(e)The formaldehyde-free latexemployed in this example is a vinyl acrylic co-polymer, available as HP31-316 NF. This formaldehyde-free latex includes1,2-benzisothiazolin-3-one, supplied as Proxel ® GXL (ARCH Chemicals),as manufactured. ^(f)No additional biocide was added to the surfacetreatment composition used in this example, other than that included inthe formaldehyde-free latex. ^(g)The formaldehyde-free biocide employedin this example is a combination of 1,2-benzisothiazolin-3-one andmethyl-4-isothiazolin-3-one, available as Acticide ® MBS (Acti-Chem).

The results shown in Example 3 demonstrate that the combination of thefire resistant back coating and the core is formaldehyde-free as definedherein, that is, the acoustical tile of this example emits less than 2μg/m³, which is below the lower LOQ of the Standard Practice. Example 4demonstrates that the acoustic tile, which includes the fire resistantback coating, formaldehyde-free latex, and the core, isformaldehyde-free as defined herein. Examples 5, 6 and 7 demonstratethat acoustic tiles, which, among other things, includeformaldehyde-free biocide as a component of the surface treatment, arealso formaldehyde-free as defined herein. Further, Examples 3-7 in Table1 demonstrate that the combination of components as used to makeacoustic tile of the present invention are also formaldehyde-free asdefined herein. Examples 3-7 are also illustrative of the preferredembodiment of the invention, in that the formaldehyde emission of thesetiles is below about 1 μg/m³.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

The invention claimed is:
 1. An acoustical tile comprising a core and asurface treatment, wherein the surface treatment comprises a surfacetreatment composition that is applied to the core, and wherein thesurface treatment composition prior to drying comprises: from about 30to about 50 weight % solvent; from about 40 to about 60 weight % filler;from about 2 to about 15 weight % TiO₂; from about 2 to about 20 weight% formaldehyde-free and non-formaldehyde-emitting latex; from about 0.25to about 1.00 weight % dispersant; from about 0.01 to about 1.00 weight% formaldehyde-free and non-formaldehyde-emitting thickener, wherein theformaldehyde-free and non-formaldehyde-emitting thickener is a materialselected from the group consisting of methyl cellulose,methylhydroxycellulose methylhydroxyethylcellulose,methylhydroxypropylcellulose, hydroxypropyl cellulose, sodiumcarboxymethylcellulose, hydroxyethylcellulose, and soy-protein derivedpolymers, or combinations thereof; from about 0.10 to about 1.00 weight% surfactant; from about 0.05 to about 0.50 weight % defoamer; and fromabout 0.01 to about 1.50 weight % formaldehyde-free andnon-formaldehyde-emitting biocide, and wherein the acoustical tile isformaldehyde-free and does not emit formaldehyde.
 2. The acoustical tileof claim 1, wherein the biocide is an isothiazolin-3-one.
 3. Theacoustical tile of claim 1, wherein the biocide is a combination of1,2-benzisothiazolin-3-one and methyl-4-isothiazolin-3-one.
 4. Theacoustical tile of claim 1, wherein the core comprises a fiber selectedfrom the group consisting of a glass fiber, a mineral wool fiber andmixtures thereof, wherein the mineral wool fiber is selected from thegroup consisting of slag wool, rock wool, basalt wool, and mixturesthereof, wherein the core further comprises a member selected from thegroup consisting of a calcium sulfate material, boric acid, kaolin clay,guar gum, sodium hexametaphosphate, and mixtures thereof, the tilecomprises a backing selected from the group consisting of bleachedpaper, unbleached paper, and kraft/aluminum foil.
 5. The acoustical tileof claim 1 further comprising zinc 1-hydroxy-2(1H)-pyridinethione. 6.The acoustical tile of claim 1, wherein the tile has a formaldehyderelease or emission that is below a quantifiable limit of about 1 μg/m³.7. The acoustical tile of claim 1, wherein the core is formed of amineral wool fiber.
 8. The acoustical tile of claim 1, wherein the tilehas a formaldehyde-free and non-formaldehyde-emitting fire resistantback coating.
 9. A formaldehyde-free acoustical tile consistingessentially of a core and a surface treatment, wherein the surfacetreatment comprises a surface treatment composition that is applied tothe core: wherein the surface treatment has a formaldehyde release oremission that is below a quantifiable limit of 1 μg/m³ and the surfacetreatment composition prior to drying comprises: from about 30 to about50 weight % solvent; from about 40 to about 60 weight % filler; fromabout 2 to about 15 weight % TiO₂; from about 2 to about 20 weight %latex that has a formaldehyde release or emission that is below aquantifiable limit of 1 μg/m³; from about 0.25 to about 1.00 weight %dispersant; from about 0.01 to about 1.00 weight % thickener that has aformaldehyde release or emission that is below a quantifiable limit of 1μg/m³ and comprises a material selected from the group consisting ofmethyl cellulose, methylhydroxyethylcellulose,methylhydroxypropylcellulose, hydroxypropyl cellulose, sodiumcarboxymethylcellulose, hydroxyethylcellulose, and soy-protein derivedpolymers, or combinations thereof; from about 0.10 to about 1.00 weight% surfactant; from about 0.05 to about 0.50 weight % defoamer; and fromabout 0.01 to about 1.50 weight % biocide that has a formaldehyderelease or emission that is below a quantifiable limit of 1 μg/m³ and isselected from the group consisting of 1,2,-benzisothiazolin-3-one,blends of 1,2,-benzisothiazolin-3-one and 2-methyl-4-isothiazolin-3-one,5-chloro-2-methyl-4-isothiazolin-3-one, blends of5-chloro-2-methyl-4-isothiazolin-3-one and2-methyl-4-isothiazolin-3-one, zinc 1-hydroxy-2(1H)-pyridinethione,blends of zinc 1-hydroxy-2(1H)-pyridinethione and zinc oxide, and2-n-octyl-4-isothiazolin-3-one; and wherein the core comprises a fiberselected from the group consisting of glass fiber, mineral wool fiberand mixtures thereof, wherein the mineral wool fiber is selected fromthe group consisting of slag wool, rock wool, basalt wool, and mixturesthereof, wherein the core further comprises a member selected from thegroup consisting of a calcium sulfate material, boric acid, kaolin clay,guar gum, sodium hexametaphosphate, and mixtures thereof; and whereinthe acoustical tile has a formaldehyde release or emission that is belowa quantifiable limit of 1 μg/m³.
 10. The acoustical tile of claim 9,wherein the core is formed of a mineral wool fiber.
 11. The acousticaltile of claim 9, wherein the tile has a fire resistant back coatinghaving a formaldehyde release or emission that is below a quantifiablelimit of 1 μg/m³.